* Use plural forms for update error notification
Replace the hardcoded 'X update(s) failed' string with Android
plural resources so the notification correctly shows '1 update failed'
vs '2 updates failed', enabling proper localization.
Fixes#3051
* Address review: rename plural key and remove comment
Rename plural key to notification_update_errors to avoid potential
conflicts with existing translated string keys. Remove leftover
comment from strings.xml.
* Revert key rename per review
Christos
88edd18d02